Many types and styles of so-called child-proof or, more properly, child-resistant, closures have been suggested for containers in which dangerous or harmful products are packaged. Some types, such as snap-on caps, may be satisfactory for solid objects like pills or tablets but do not establish liquid tight seals when they are closed. Other types involving the use of mating threads on the cap and container neck have been suggested for packaging liquid materials, but most of these are either too complicated, comprise two or more separately moldable parts which must be assembled and are thus costly, or require extremely complicated molds thus increasing the cost of manufacture. Others more successful in retaining liquids in containers have been developed which place the mating threads in one concentric skirt and have the child-resistant locking means on other attached elements, therefore these closures require substantial quantities of the material from which they are fabricated and thus also are relatively costly.
It is, therefore, the principal object of the instant invention to provide a child-resistant cap and neck finish for a container which will be liquid tight when closed, which is a single unitary piece, which has effective threads for tightly sealing the container and a simple, yet effective, child-resistant locking means.
Yet another object of the instant invention is to provide a child-resistant cap and neck finish for a container wherein the container neck has threads of "standard pitch" and thus will accept a simple threaded cap of the type long used for closing containers but also can be utilized in combination with a child-resistant cap according to the invention when it is desired to make the closure child-resistant.